Countries all over the world are implementing initiatives in response to the climate challenge. One such initiative is the H21 Leeds City Gate project, which aims to convert the United Kingdom’s natural gas network to 100% hydrogen.
Does that sound unrealistic? It shouldn’t. Particularly when we remember that during the 1960s and 70s the UK underwent a very smooth and successful conversion of its entire gas network from town gas, which contains 50% hydrogen, to natural gas. The conversion to hydrogen, which could be conducted with similar efficiency and lack of disruption, would have a huge and positive impact.
Making the invisible visible
The H21 Leeds City Gate project was launched in 2016 by Northern Gas Networks. The project is headed by Dan Sadler, a Chartered Engineer with nearly 20 years industry experience. He spoke to cH2ange about the origins of the project:
“In many ways the gas industry is an invisible industry. When people talk about reducing carbon emissions, they mention wind farms and solar panels, no one talks about the gas network. For the H21 project we needed to make the gas industry visible, as well as benefits of gas and the gas networks to the domestic and global energy market. We chose Leeds as the starting point based on geography and geology but also being the UK’s third biggest city, the scale is large enough to turn heads and illuminate the project.”
“H21 is the first project of its kind in the world, so it’s no surprise that it’s attracted a global following.”
The project is designed to enable the country to meet emissions reduction targets as defined in the UK’s Climate Change Act. To achieve this, the H21 concept extend beyond Leeds showcasing an incremental conversion strategy for the UK. Later this year the project will publish a proposal on converting the whole of the north of England to hydrogen (H21 North of England). “That’s on a scale 12 times as big as Leeds, requiring a constant output of 10 GW of hydrogen,” commented Dan.
Ultimately the project aims for a UK-wide conversion to hydrogen, which would reduce carbon emissions from heating in excess of 80% “Converting the UK gas grid to hydrogen will be a major step towards meeting the UK’s carbon reduction targets. Currently, over 30% of all UK carbon emissions come from domestic heating and cooking”, explained Dan.
“Both the existing medium pressure and low pressure gas distribution networks have sufficient capacity to convert to 100% hydrogen with relatively minor upgrades.”
The H21 project’s objective is to use steam methane reformers (SMRs) to strip the carbon atom from natural gas to generate hydrogen for the gas network. “The SMRs would be linked to carbon capture and storage (CCS) to safely lock away the majority of the carbon released by this process, bringing emissions down from 180 to below 50 gm/kWh CO2 equivalent,” said Dan. The project sets out proposals to install a hydrogen production capacity of 1,025 MW by 2025, provided by four SMRs fitted with CCS located at Teesside. A Hydrogen Transmission System capable of transporting the peak supply requirement will connect the SMRs to the area to be converted. Moreover, it has been proven that both the existing medium pressure and low pressure gas distribution networks have sufficient capacity to convert to 100% hydrogen with relatively minor upgrades.
Reaching the peak
An important aspect of the H21 Leeds feasibility study was to show that a hydrogen gas network could cope with the huge seasonal variation in demand. “Leeds needs 6 TWh of energy per year, which requires an average of 732 MW for every second of every day. Our feasibility study has a production design point of 140%, which provides the overproduction necessary to cope with the winter demand, but still allows you to keep the amount of storage to a minimum to reduce costs,” explained Dan.
Regarding storage, H21 will make use of the geology of north-east England. The region has access to extensive CCS via extensive known geology deep under the North Sea, along with salt deposits that can be used to manage the inter-seasonal and intraday swings in demand. For example salt caverns in Teesside will provide the necessary capacity to deal with intraday storage (4,000 MWh); and salt caverns on the East Humber coast will provide inter-seasonal storage of up to 40 days (700,000MWh) of the maximum average daily demand in the coldest year.
A smooth transition
Such a large-scale conversion is not without precedent. For 150 years the UK gas industry (like the rest of the world) used locally manufactured town gas, which contained around 50% hydrogen. When natural gas was discovered in the North Sea, a very successful nationwide conversion program began in the 1960s.
“We need credible, scalable solutions — and we need them today.”
Hydrogen conversion would follow a similar process. Small enough areas of the network would be isolated so that a workforce could convert the area (appliances) within a maximum of 5 days. Meaning customers would only be off the network a very few days.
Multiple benefits
H21 is a major step towards meeting the UK’s carbon reduction targets, but this is by no means the only benefit. Other key advantages are reusing a national paid for asset (the existing gas infrastructure) avoiding economic losses, maintaining choice for customers and causing much less disturbance than other decarbonization options in the highways and the homes. “For example,” commented Dan, “to have a fully electric society we’d have to reinforce the entire electric network because it doesn’t have the capacity to displace oil and heat.”
“Heavy haulage, buses, garbage trucks, cars… can all be fuelled on hydrogen.”
Furthermore, because gas networks are designed to meet the “1 in 20 peak” (to maintain energy security in very cold conditions that typically occur once every 20 years), there is an inherent overcapacity in the network that can be utilized. Dan explained:
“The H21 project will create bulk availability of hydrogen across the network. Hydrogen fuelling stations can be built to support the rapid decarbonization of transport. Heavy haulage, buses, garbage trucks, cars… can all be fuelled on hydrogen. Alongside battery-electric cars this will help displace oil from transport, which will be vital in terms of climate change and will save lives by improving air quality, since hydrogen vehicles emit no tailpipe pollutants.”
Clean first, then green
In future, hydrogen production from electrolysis powered by renewable energy would be a zero-emissions solution, but such technology is not yet able to deliver the quantities of hydrogen required.
“Customers don’t have to make significant changes to the way they use energy”
“There is a collective obsession for ‘green’, which is to the detriment of ‘clean’. We’ve got 30 years to meet very demanding climate commitments. Transitioning to an entirely green, all electric energy system on a global scale within this time frame is unrealistic. We need credible, scalable solutions — and we need them today. H21 would bring about the onset of the hydrogen economy, which would have huge benefits in terms of carbon emissions and air pollution. But to do this we need technology like CCS that has been proven to work throughout the world. As the global trade of green hydrogen increases, we can back away from CCS. But that’s impossible within the next 30 years,” said Dan.
Global impact
H21 is the first project of its kind in the world, so it’s no surprise that it’s attracted a global following. “Australia, China, Japan, Holland, Germany, France, New Zealand, Canada, Ireland, Norway… everyone is looking at H21 because collectively we are starting to realize the true scale of the climate change challenge and the incredible opportunity the h21 concept represents to meet that challenge,” said Dan.
“If we can make this work, meeting climate change obligations is guaranteed because the strategy and technology is on the right scale and can be delivered within the timelines”
Conversion of the gas grid to hydrogen would not only enable climate change obligations to be met, but it would foster a hydrogen society that would solve the air pollution issue and facilitate the expansion of renewable power by providing energy storage to stabilize the system.
This can all be achieved using technology that is available today. “Customers don’t have to make significant changes to the way they use energy”, concluded Dan. “Its an easy idea to appreciate: ‘re-use existing infrastructure, help displace oil and solve air quality problems saving lives, maintain choice for customers (gas or electric), establish a global network for balancing clean/green energy (through hydrogen), create jobs, and meet climate change obligations. Why wouldn’t we want to do this? If we can make this work, meeting climate change obligations is guaranteed because the strategy and technology is on the right scale and can be delivered within the timelines”.
